Circuit breaker



Filed July 23 INVENTOR Goff/Afi ajaellrer:

WITNESSES I ATTO'RNEY Patented June 10, 1930 UNITED STATES PATENT OFFICEGOTTLIEB SPEISEB, OF NUREMIBERG, GERMANY, ASSIGNOR TO WESTINGHOUSE ELEC-TRIG & MANUFACTURING COMPANY, .A CORPORATION OF PENNSYLVANIA CIRCUITBREAKER Application filed July 23, 1925, Serial No. 45,522, and inGermany .I'une 30, 1924.

My invention relates to circuit breakers and particularly to circuitbreakers for controlling circuits, wherein alternating current inductionmotors and electric lamps having metal filaments are connected.

It is well known that the current required for starting an alternatingcurrent induction motor or for starting the illumination of metalfilament lamps is considerably more than is required for normaloperation of the motors or lamps.

It is an object of my invention to provide an automatic circuit breakerwherein the circuit is caused to be interrupted when the current in thecircuit is slightly above the normal current requirements, but whichwill not open the circuit in response to the excessive current requiredfor starting the motors or lamps.

Another object of my invention is to provide a circuit breaker having acurrent responsive trip coil which is provided with a circuit connectedin parallel for the purpose of carr ing the excess starting current andwhich is caused to be opened within a predetermined time after thecircuit breaker has been closed, or to be opened manually a shortinterval after the circuit breaker is closed.

Another ob'ect of my invention is to provide a circuit reaker having theabove noted characteristic that is simple in construction and whichrequires but a few parts that ma be inex ensivel manufactured.

'l hese an other jects that will be made apparent throughout the furtherdescription of my invention are attained by means of the circuit breakerapparatus hereinafter described and illustrated in the accompanyingdrawings, wherein;

ig. 1 is an elevational view of the circuit breaker apparatus shownmounted in a housing that is illustrated in section, and

Fig. 2 is an elevational view similar to that of Fig. 1 and showing amodified form of tripping mechanism for the circuit breaker.

Referring to the drawings, the circuit breaker includes a housing 3,having a base member 4 and within which the circuit breaker is mounted.The circuit breaker comprises a stationary contact member 5 secured tothe base member and a movable contact member 6 that is mounted upon aflexible conductor member 7 which is secured to the terminal device 8.

The movable contact or switch member 6 is actuated by means of anoperating handle 9 that is pivoted to a shaft 10 mounted on the sidewalls of the housing. The operating handle operates the contact member 6through the medium of the toggle links 11, 12 and 13 that are pivotallyconnected to the handle and to one another by pivot shafts 14, 15 and 16and to the housing pay mians of a pivot shaft 17, as indicated in Theshaft 16 engages the flexible member 7 and serves to retain the contactmember 6 in closed position when the links 11 and 12 are in theover-center position shown in Fig. 1. The adjustment of the relativeposition of the links 11 and 12 when in the over center position, isaccomplished by means of the adjusting screw 18.

When the operating handle is moved in a clockwise direction, the tog 1elinks 11 and 12 collapse and permit the iixible member 7 to move thecontact mom-ber position.

In order to trip the circuit breaker to open position under shortcircuit and overload conditions, a trip coil 19 is provided which ismounted upon a supporting member 20. The coil is connected in serieswith the circuit breaker contacts and is provided with a movablearmature 21 that is moved upwardl into engagement with the knee of thetogg e links 11 and 12 and which trips the toggle and circuit breaker toopen posi- 6 to open tion in response to an abnormal overload current01' a short circuit.

In order to prevent abnormal starting current from causing the trip coilto open the breaker, a circuit is provided that is connected in parallelto the trip coil. This circuit comprises a resistance element 2,conductor 22, stationary switch terminal contact 23, a bimetal thermalswitch element 24 and conductor 26. The element 24 is mounted upon thesupporting member 20 and constitutes a switch for controlling theparallel circuit. The bimetal element is normally biased in engagementwith the contact member 23 and is heated by a heating coil 25 that isconnected in series with the trip coil 19 by means of the conductors 27and 26. The resistance in the parallel circuit is less than that of thetrip coil and consequentl so long as the thermal switch element 24 1s inengagement with the contact 23, the major portion of the startingcurrent will pass through the parallel circuit and the current thentraversing the coil19 is insufiicient to trip the circuit breaker.

The operation of the circuit breaker is as follows; assuming that thecircuit breaker has just been moved to closed position, current entersthrough the feed conductor 27 and passes through the heating coil 25,conductor 26, coil 19, conductor 28, terminal 8, flexible switch member7, contact member 6, stationary contact member 5 and to the feedconductor 29. At such time, the parallel circuit is closed and currentpasses through both the trip coil and the parallel circuit until thebimetal is moved to open position by reason of the heating action of thecoil 25. The conductor 29 may be the feed conductor in which event thiscoil and parallel circuit will not be energized when the circuit breakeris open. As it takes a few seconds for the motor to come up to normalspeed or the lamps to be heated to their normal incandescence, it isnecessary to retain the terminal element 24 in engagement with thecontact member 23 a corresponding period of time, after which normalcurrent conditions are restored and all current may then be permitted topass through the coil.

It will be seen from the foregoing that the circuit breaker will notopen under the starting current conditions and will open the circuitunder overload or short circuit conditions.

A modified form of circuit breaker is illustrated in Fig. 2 wherein thecircuit breaker mechanism is similar to the mechanism shown in Fig. 1with the exception that the operating handle 9 is provided with anextension 31 which engages a flexible switch member 32 which correspondsto the thermal element 24 of the device previously described. Theflexible switch member 32 serves to close a parallel circuit connectedin parallel to the trip coil 19, as indicated in ig. 2.

When the operating lever 9 is in the position shown inFig. 2, thecircuit breaker contacts 5 and 6 are maintained in closed position andthe extension 31 holds the switch element 32 in open position. Theextension 31 is so disposed on the operating handle that it engages theswitch element 32 and moves it to open position just after the contactmembers 5 and 6 have been moved into engagement by the counterclockwiseclosing movement of the operating handle. In this construction it isnecessary for the operator to arrest the final movement of the operatinglever for a few seconds after the contacts 5 and 6 have closed thecircuit.

As the operating handle is retained in closed position by the togglelinks, it will be seen that the switch member 32 is normally retained inopen position, and that all of the current passing through the circuitbreaker traverses the trip coil which then serves to open the circuitbreaker under overload or short circuit conditions.

While I have described and illustrated but two embodiments of myinvention, it will be apparent to those skilled in the art that variouschanges, modifications, substitutions, additions and omissions may bemade in the apparatus illustrated without departing from the spirit andscope of my invention, as set forth in the appended claims.

I claim as my invention:

1. The combination with a circuit breaker having a current responsivetrip device for releasing the circuit breaker to open position underpredetermined current conditions, of a normally closed circuit connectedin parallel to the trip device, a thermal responsive switch element foropening the said circuit and a heating coil for the said elementconnected in series with the said coil for maintaining the switchelement at a temperature under normal current conditions sufficient tomaintain the element in open position.

2. A circuit breaker comprising a movable switch member, means forreleasably retaining the switch member in closed position, a trip coilfor releasing the said means in response to predetermined currentconditions, a circuit connected in parallel with the trip coil and acurrent responsive switch element for controlling the said circuitnormally biased in closed position and movable to open position inresponse to predetermined current conditions, the said element beingadapted to remain in open position under normal current conditions.

3. A circuit breaker comprising a movable switch member, means forreleasably retaining the switch member in closed position, a trip coilfor releasing the said means in response to predetermined currentconditions, a circuit connected in parallel with the trip coil and a.current res nsive switch element for controlling the said circuitnormally biased to closed position and retained in open position undernormal current conditions.

In testimony whereof, I have hereunto subscribed my name this 18th dayof June,

GOTTLIEB SPEISER.

